Perhaps I can help my noble friend. Perhaps I misunderstand the position but he speaks from the point of view of adjusting the rest of the tax system in the event of the impact of a Scottish tax. But what would happen if this was done the other way round? What would happen if the Treasury proposed to change the tax system in a way that would adversely affect the revenue base of the Scottish Parliament? As I understand it, as the Bill stands, there would be no requirement either to compensate it or to seek leave to do so. Perhaps I misunderstand what these powers enable the Treasury to do but that is my understanding. If so, surely it would be appropriate to seek the consent of the Scottish Parliament. Perhaps my noble friend is suggesting that that consultation would involve asking the Parliament and allowing the ability to ignore it. I can see a difficulty here. For example, suppose some new rule were to be introduced to provide substantial tax relief for particular categories-charities, pensions or some other relief. That could greatly reduce the tax base for the Scottish Parliament and, as far as I can see, there is no provision in the Bill to compensate it for that. There ought to be some basis on which the Parliament's consent is sought.
I feel as if I have become a sort of advocate for devo-max on this, because I am making a case that might be made by one of the enthusiasts for devolution. However, I am doing that from the point of view that, if we are going to go down this track, we have to make it workable, and I am not sure that it is.